This application is based on Patent Application Nos. 121832/1998 and 121833/1998 both filed on Apr. 15, 1998 in Japan and the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a feeding apparatus and a printing apparatus which can be coupled with each other, and a feeding control method. More particularly, the invention relates to a feeding apparatus and a feeding control method for feeding a printing medium, such as a paper or the like, to a printing apparatus, and a printing apparatus for printing information, such as a document, graphic image and so on processed by an information processing system, on a printing medium, such as a paper or the like.
In the present invention, a feeding apparatus and a feeding control method perform feeding of a printing medium automatically in accordance with a command from a printing apparatus to which the feeding apparatus is connected. Therefore, they are also called an automatic feeding apparatus and an automatic feeding control method.
2. Description of the Related Art
Demand in the market for downsizing and weight lightening for a printer as a printing apparatus has been growing similarly to other various devices. For satisfying such demand, downsizing and weight lightening in the printer have progressed significantly. Seeking downsizing of the printer, there has been proposed a printer, in which a main body portion of the printer performing image printing and an automatic sheet feeder (hereinafter referred to as xe2x80x9cASFxe2x80x9d) portion for feeding a plurality of stacked sheets as printing media to an image forming portion one by one are separated, as disclosed in Japanese Patent Application Laid-open No. 4-303336 (1992). Namely, the ASF portion is made independent of the main body of the printer for external attachment. On the other hand, not only in the small size printer, but also in a printer having a plurality of paper feeding openings or a printer permitting only manual paper feeding, there has been conventionally known of ASFs which can be externally installed. It should be noted that various media in addition to paper are included as the printing media.
In the ASF disclosed in Japanese Patent Application Laid-open No. 4-303336, namely, in the ASF to be externally installed on the printer, a drive system of a feeding roller feeding a sheet one by one is constructed. The drive system is constructed by coupling driving power transmission means, such as a gear exposed outside of the ASF, and driving power transmission means exposed outside of a printer body. And, a driving force, such as a motor within the printer body, is used as the driving force of the feeding roller. In such driving method, since it becomes unnecessary to independently provide a driving source, such as a motor or the like and an electric source on the side of the ASF, the ASF can be constructed at low cost and light weight. However, on the other hand, for limitation of freedom of mechanical components arrangement in the ASF, it is not always possible to set optimal position for the ASF for downsizing and stability of performance.
On the other hand, for example, as disclosed in Japanese Patent Application Laid-open No. 9-194085 (1997), there has been proposed the ASF incorporating a motor as a driving source of the feeder roller for external installation. In this case, freedom of the mechanical components arrangement is increased to permit arrangement of the parts of the paper feeding mechanism independent of the construction of the printer body. Upon making the ASF perform paper feeding operation, through electrical contacts provided on a mating portion between the printer body and the ASF, a controller provided within the printer body applies an electrical signal to the motor for driving the paper feeder roller for driving the latter.
However, a sheet, on which an image is printed by the printer, is not limited to a plain paper, but can be of wide variety of size and thickness, such as a postcard, cardboard, envelope and so on. On the other hand, due to progress of printing technology in printers, such as that of an inkjet type and so on, more fine ink droplet or high and low density ink droplets can be ejected to permit formation of a high quality image with higher definition and superior tone reproducibility. For making high image quality effective depending upon purpose, special sheets, such as a coated paper, a glossy paper, a glossy film, an OHP film, a cloth, an iron transfer paper and so on have been developed.
In the ASF which can be installed in the printer, there has been required a performance for certainly feeding various kinds of sheets without causing any problem. However, the sheets as the printing medium should differentiate optical feeding conditions depending upon thickness, sizes or surface characteristics thereof.
Since the conventional ASF, which can be installed on the printer as set forth above, has no feeding operation control means for driving the feeding roller by driving the motor, control of the paper feeding operation by the ASF is performed by the printer. Therefore, control means within the printer is required to have feeding operation control function having feeding conditions adapted to various sheets. Therefore, in addition to control for the printer body, the necessity set forth above makes control software large and complicated.
On the other hand, in some printer bodies, it is required to use an external ASF dedicated for postcard feeding, an external ASF for continuous sheet feeding and so on in addition to the normal external ASF, or to use a new type and improved type of external ASF. If feeding operation control of the ASF is different even in part, the printer body has to have control functions for all of the feeding operation. Therefore, software in the printer body becomes further complicated, or in worse case, modification of the software becomes necessary, and a problem in compatibility is possibly caused. On the other hand, a large number of printer bodies are in the market so that modification of the software on the side of the printer body is substantially impossible. In the alternative, upon providing a new external ASF, it is required that paper feeding can be performed without causing any problem by the existing control function for the feeding operation which has been provided in the printer. Therefore, designing freedom of ASF is restricted significantly.
On the other hand, the ASF, such as that disclosed in Japanese Patent Application Laid-open No. 4-303336, is generally constructed with a pressure plate, on which sheets are stacked, a paper feeding roller for feeding sheets as the printing media stacked on the pressure plate one by one, a paper transporting roller and a pinch roller for pinching and transporting the sheets fed from the feeding roller. As the printing medium, in addition to paper, various other media should be included. In the sheet feeding operation, at first, the feeding roller on the upstream side in a transporting direction is driven for rotation, so that the sheet is fed. Thus the tip end of the sheet abuts with a nip portion formed by the transporting roller and the pinch roller on the downstream side in the transporting direction. Subsequently, the sheet is forced into the nip portion by further rotating the feeding roller to perform registration. Thereafter, by driving the transporting roller, the sheet is transported to be fed into a printing portion of the printing apparatus.
On the other hand, in so-called positioning top of sheet, by rotation of the transporting roller, the transporting roller grips the tip end portion of the sheet abutted to the nip portion. Upon such positioning top of sheet, when the feeding roller is in pressure contact with the rear end portion of the sheet, significant back tension should be exerted on the sheet on the downstream side in the transporting direction, so that precision of positioning top of the sheet is degraded. In order to prevent this, an arc-shaped roller is used as the feeding roller, or a construction to forcedly release depression of the pressure plate onto the feeding roller by means of a cam or so on can be employed. By such construction, when the feeding roller is in a particular rotational phase, load is not applied to the sheet. In this case, upon positioning top of the sheet, it is frequently performed to drive both of the transporting roller and the feeding roller so as not to exert the back tension on the sheet by the feeding roller.
However, in the conventional ASF as set forth above, problems are still caused as follows.
Namely, in the conventional ASF, upon positioning top of sheet, driving of the transporting roller and the feeding roller are initiated simultaneously. However, in practice, due to factor of backlash of the gears, delay in transmission of driving force, the rotation start timing of the paper feeding roller on the upstream side in the transporting direction can be slightly delayed from the rotation start timing of the transporting roller on the downstream side in the transporting direction. In this case, the feeding roller should exert back tension to the sheet. As a result, upon positioning top of the sheet, precision of feeding can be disturbed to affect precision of the print start position. On the other hand, when a common motor is used for driving the transporting roller and the feeding roller, it is possible that reduction ratios of the transporting roller and the feeding roller cannot be the same due to restriction of arrangement of the components. As a result, if the peripheral speed of the feeding roller is lower than the peripheral speed of the transporting roller, back tension can be exerted on the sheet. Therefore, upon positioning top of the sheet, adverse influence for precision of the print start position is caused due to disturbance of precision of sheet feeding. Conversely, if the peripheral speed of the feeding roller is higher than the peripheral speed of the transporting roller, bending of the sheet can be caused due to difference in speed of the rollers.
It is an object of the present invention to provide a feeding apparatus, a printing apparatus and a feeding control method, which can significantly simplify a control software on a side of the printing apparatus and can acquire designing freedom of the feeding apparatus.
Another object of the present invention is to provide a feeding apparatus, a printing apparatus and a feeding control method, which can certainly stabilize precision of feeding of a printing medium and can be more reliable.
In a first aspect of the present invention, there is provided a feeding apparatus which is installed to a printing apparatus printing an image on a printing medium and can feed the printing medium to the printing apparatus comprising:
a communication port for communicating with the printing apparatus; and
control means for executing a process depending upon a command signal received from the printing apparatus through the communication port and transmitting a response signal depending upon a result of the process to the printing apparatus through the communication port.
In a second aspect of the present invention, there is provided a printing apparatus installed to a feeding apparatus and printing an image on a printing medium comprising:
a communication port for communicating with the feeding apparatus; and
control means for transmitting a command signal to the feeding apparatus through the communication port, for receiving a response signal responsive to the command signal from the feeding apparatus through the communication port, and for performing control depending upon the response signal.
In a third aspect of the present invention, there is provided a feeding control method feeding a printing medium from a feeding apparatus installed to a printing apparatus, and controlling printing of an image on the printing medium by a printing head of the printing apparatus, comprising:
step of transmitting a command signal to the feeding apparatus through a communication port for communicating with the feeding apparatus;
step of executing a process depending upon the command signal received from the printing apparatus through the communication port and transmitting a response signal depending upon a result of the process through the communication port; and
step of performing a control depending upon the response signal received from the feeding apparatus through the communication port.
In a fourth aspect of the present invention, there is provided a feeding apparatus which is installed to a printing apparatus having a transporting roller for transporting a printing medium in a predetermined transporting direction and printing an image on the printing medium, and the feeding apparatus can feed the printing medium to the printing apparatus comprising:
stacking means for stacking the printing medium;
a feeding roller for feeding the printing medium stacked on the stacking means toward a transportation start position for the transporting roller; and
control means for demanding that the printing apparatus perform transportation of the printing medium by the transporting roller, when a predetermined delay period from initiation of feeding the printing medium by the feeding roller in a transporting direction in which the printing medium is transported by the transporting roller is passed, after feeding the printing medium to the transportation start portion by the transporting roller.
In a fifth aspect of the present invention, there is provided a printing apparatus printing an image on a printing medium by using a printing head, the printing medium being fed by a feeding roller, comprising:
a transporting roller for transporting the printing medium in a predetermined transporting direction; and
control means for transporting the printing medium by the transporting roller, when a predetermined delay period from initiation of feeding the printing medium by the feeding roller in a transporting direction in which the printing medium is transported by the transporting roller is passed, after feeding the printing medium to the transportation start portion by the transporting roller.
In a sixth aspect of the present invention, there is provided a printing apparatus installed to a feeding apparatus feeding a printing medium to a predetermined feeding direction by a feeding roller, the printing medium being fed from the feeding apparatus to the printing apparatus, the printing apparatus printing an image on the printing medium by using a printing head, comprising:
a transporting roller for transporting the printing medium fed from the feeding apparatus in a predetermined transporting direction; and
control means for transporting the printing medium by the transporting roller, when a predetermined delay period from initiation of feeding the printing medium by the feeding roller in a transporting direction in which the printing medium is transported by the transporting roller is passed, after feeding the printing medium to the transportation start portion by the transporting roller.
In a seventh aspect of the present invention, there is provided a feeding control method for transporting a printing medium fed by a feeding roller, in a predetermined transporting direction by a transporting roller, comprising a step of:
transporting the printing medium by the transporting roller, when a predetermined delay period from initiation of feeding the printing medium by the feeding roller in a transporting direction in which the printing medium is transported by the transporting roller is passed, after feeding the printing medium to the transportation start portion by the transporting roller.
According to the present invention, the feeding apparatus can perform a part of control of control means incorporated in the conventional printing apparatus so that significant simplification of the control program on the side of the printing apparatus is permitted.
For example, when the control means of the external feeding apparatus has an optimal feeding operation control program corresponding to various media, the printing apparatus completes feeding operation simply by transmitting a feeding command signal to the external feeding apparatus and receiving the feeding completion signal from the external feeding apparatus. Therefore, it becomes unnecessary to provide feeding operation control programs adapted to various printing media in the printing apparatus. Accordingly, the control software in the printing apparatus can be simplified significantly.
On the other hand, for example, if an external feeding apparatus dedicated for postcard, an external feeding apparatus dedicated for continuos sheet or an external feeding apparatus which will be developed in the future have the feeding operation control program similar to that of the external feeding apparatus of the present invention, the printing apparatus may complete feeding operation simply by transmitting a feeding command signal to the external feeding apparatus and receiving the feeding completion signal from the external feeding apparatus. Therefore, another feeding apparatus or new external feeding apparatus may be used easily.
Furthermore, for example, as long as another feeding apparatus is set at the position of the communication port at a position for establishing communication with the printing apparatus, arrangement freedom of other components is not limited. Therefore, high freedom in designing can be provided upon designing the new type or improved type feeding apparatus.
On the other hand, the external feeding apparatus according to the present invention can read the result of detection of the feeding detection sensor within the printing apparatus via the communication port. By this, on the side of the feeding apparatus, a sensor detecting the printing medium becomes unnecessary to contribute for lowering cost. Furthermore, by arranging the feeding detection sensor within the printing apparatus in the vicinity of the feeding roller, the printing medium can be fed into the printing apparatus at higher precision. On the other hand, by directly reading whether the feeding detection sensor detects the printing medium or not through the communication port not via the control portion of the printing apparatus, it becomes unnecessary to repeat communication with the printing apparatus to eliminate time loss. Accordingly, as compared with a case in which the feeding apparatus does not have the detection sensor for the printing medium, feeding operation can be performed at a completely comparable period.
On the other hand, by supplying a power for driving the feeding apparatus control portion or the feeding motor from the printing apparatus through the communication port, the feeding apparatus does not need to have the electric source. Therefore, with respect to the feeding apparatus, downsizing, space-saving, reducing of weight, cost-down or improvement of handling ability in cordless construction is contributed.
Furthermore, by the present invention, rotation of the feeding roller is started at slightly earlier timing than starting of rotation of the transporting roller. Therefore, upon initiation of rotation of the transporting roller, the feeding roller will not exert back tension on the printing medium.
On the other hand, by separately providing motors for independently driving the transporting roller and the feeding roller, the peripheral speeds of these rollers can be varied freely. Therefore, if the transporting roller and the feeding roller are driven for rotation simultaneously, the appropriate peripheral speed, at which disturbance of precision in feeding can be minimum, can be set.
Thus, upon positioning top of the printing medium by the transporting roller, precision in feeding can be certainly stabilized to provide more reliable feeding apparatus, feeding control method and the printing apparatus.
On the other hand, as another effect by providing the motors for driving the transporting roller and the feeding roller independently, the portion including the transporting roller and its driving motor are provided on the side of the printing apparatus and the portion including the feeding roller and its driving motor are provided on the side of the feeding apparatus. As a result, the printing apparatus superior in portability and the external feeding apparatus superior in operability can be realized.